Model estimates of net primary productivity,evapotranspiration, and water use efficiency in the terrestrial ecosystems of the southern United States during 1895–2007

The effects of global change on ecosystem productivity and water resources in the southern United States (SUS), a traditionally ‘water-rich’ region and the ‘timber basket’ of the country, are not well quantified. We carried out several simulation experiments to quantify ecosystem net primary productivity (NPP), evapotranspiration (ET) and water use efficiency (WUE) (i.e., NPP/ET) in the SUS by employing an integrated process-based ecosystem model (Dynamic Land Ecosystem Model, DLEM). The results indicated that the average ET in the SUS was 710 mm during 1895–2007. As a whole, the annual ET increased and decreased slightly during the first and second half of the study period, respectively. The mean regional total NPP was 1.18 Pg C/yr (525.2 g C/m²/yr) during 1895–2007. NPP increased consistently from 1895 to 2007 with a rate of 2.5 Tg C/yr or 1.10 g C/m²/yr, representing a 27% increase. The average WUE was about 0.71 g C/kg H₂O and increased about 25% from 1895 to 2007. The rather stable ET might explain the resulting increase in WUE. The average WUE of different biomes followed an order of: forest (0.93 g C/kg H₂O) > wetland (0.75 g C/kg H₂O) > grassland (0.58 g C/kg H₂O) > cropland (0.54 g C/kg H₂O) > shrubland (0.45 g C/kg H₂O). WUE of cropland increased the fastest (by 30%), followed by shrubland (17%) and grassland (9%), while WUE of forest and wetland changed little from the period of 1895–1950 to the period of 1951–2007. NPP, ET and WUE showed substantial inter-annual and spatial variability, which was induced by the non-uniform distribution patterns and change rates of environmental factors across the SUS. We concluded that an accurate projection of the regional impact of climate change on carbon and water resources must consider the spatial variability of ecosystem water use efficiency across biomes as well as the interactions among all stresses, especially land-use and land-cover change and climate.     

美国丹佛樱桃溪生态廊道人工修复成功案例

文章根据笔者在美国丹佛市考察期间的部分见闻整理而成,通过现场观察和资料收集,对丹佛樱桃溪生态廊道人工修复工程项目做了全面介绍,其中社会参与、财务公开、科普宣传及坡面治理等经验值得我国借鉴。       

Fuelling the fisheries subsidy debate: Agreements, loopholes and implications

There is a general consensus that most subsidies to fisheries, particularly fuel subsidies, are harmful to both the economy and the environment. As the World Trade Organization struggles to come to an agreement on fisheries subsidies, understanding the position of the negotiating countries is crucial. As we move toward more sustainable regulations, we must ensure that no loopholes exist for countries to evade binding regulations. In this note, we use the example of the United States to illustrate how arguments for exemptions can lead to such loopholes. The United States provides interesting insight, as it appears that their support for a ban on fisheries subsidies may be contingent upon a legal pun, which would allow them and other countries to carry on subsidizing fuel to their fishing fleets into the future.     

An appraisal of Miscanthus x giganteus cultivation for fly ash revegetation and soil restoration

The objective of this study was to investigate the potential of Miscanthus x giganteus (MxG) for fly ash (FA) revegetation and soil restoration. To evaluate its growth ability on FA, plant development during pot experiments was compared to that obtain in a reference soil. Several physico-chemical parameters (pH, conductivity, dissolved organic carbon, ammonium, nitrite, nitrate, phosphate and potassium contents) and microbiological parameters (enumeration of total, ammonia oxidising and nitrite oxidising culturable bacteria and community diversity analysis) were investigated after plant growth. Plants demonstrated an adaptation to the FA substrate, with an average stem length and biomass production that was half of that observed in the reference soil. Lower chlorophyll contents were measured but the absence of necrosis symptom and hydration rates of aerial parts above 70% suggested physiological adaptation of plants to the FA substrate. Moreover, significant organic carbon inputs could be measured in FA leachates after 17 weeks of laboratory cultivation, which could be related to the establishment of MxG rhizosphere. Besides, the emergence of specific bacterial phylotype could be reported at the FA-root interface. Analysis of FA leachates in planted pots also showed marked decreases of nitrate but increases of nitrite contents, indicating a nitrogen cycle restart. Field trials confirmed the growth potential of MxG directly on FA, without any requirement of additional landfill soil amendment. Finally, we believe that fly ash revegetation with MxG could be an effective strategy for cost effective and long term FA disposal site rehabilitation.     

摘穗与秸秆粉碎复式作业机构设计与试验

设计了一种摘穗与秸秆粉碎复式作业机构.该机构主要由摘穗板、一对拉茎辊和一个切割刀辊组成.拉茎辊带有凸棱,凸棱上按一定间隔设有开口,切割刀辊上装有缺口圆盘刀片,刀片与拉茎辊凸棱的开口配合,茎秆下拉时,切割刀辊将茎秆切碎,一套机构实现摘穗和秸秆切碎2个功能.建立了茎秆下拉运动方程,分析了茎秆在机构间的运动规律,理论上证明了茎秆下拉的运动轨迹具有较好的直线度.初步试验表明,该机构的摘穗效果良好,籽粒损伤率和果穗损失率低、茎秆折断减少,功耗是摘穗机构与秸秆切碎机构分置时的35％,节能效果显著.     

中国与美国及新西兰牛奶兽药残留监测计划的比较

目的：比较中国与美国及新西兰牛奶兽药残留监测计划的差异和不足,为完善我国牛奶兽药残留监测计划提供参考。方法：收集2008-2011年中国、美国及新西兰的牛奶兽药残留监测计划的数据,比较各个国家实施监测计划的药物种类、样本量以及实施结果。结果：我国与美国及新西兰牛奶兽药残留监测计划相比,监测药物种类与美国及新西兰相近,但检测量少,难以覆盖所有牧场;2011年度的中国与美国及新西兰牛奶抗生素残留监测的检测结果为：中国的检出率高于美国和新西兰（P〈0．05）,有统计学意义。建议在监测计划中扩大监测范围,增加检测量,使监测计划能覆盖更多地区和牧场。     

Pre-maturity α-amylase in wheat: The role of abscisic acid and gibberellins

The occurrence of pre-maturity α-amylase (PMA) is a major cause of poor bread-making quality (low Hagberg Falling Number) in wheat grain. In susceptible genotypes, it involves the excessive accumulation of high isoelectric point (pI) α-amylase in mature grain prior to germination and in the absence of pre-harvest sprouting. Several factors regulate PMA formation in developing grain, including genotype, agronomy, and environmental conditions. In particular, a cold period during mid-grain development has been found to be a major stimulus for PMA induction. Although the factors affecting the PMA occurrence are well known, little is known about the molecular mechanism governing its induction. The plant hormones abscisic acid (ABA) and gibberellins (GAs) influence various aspects of grain development, and it has been suggested that PMA involves changes in the amount of these hormones or the sensitivity of the grain to these hormones. This review summarizes recent studies investigating the role of ABA and GAs in PMA induction and PMA occurrence.     

英国公有公营的百年林业梦

自1919年以来的近100年,英国在政府公共投资支持下建立了以林业委员会为核心、以国营林业企业为主体的林业经营管理体制,先后通过林业定居点建设、法正林经营和实行小型林主计划等措施培育和经营人工林,为缓解经济萧条危机和解决第二次世界大战期间英国的木材供应问题做作出了积极的努力。进入20世纪90年代以后,对这个体制的私有化改革呼声开始困扰英国公有公营的百年林业梦,也为林业经济学者留下了值得思考的问题。     

美国高校计算机基础教学的启示

研究总结了美国高校计算机基础教学与我国相比的差异,分析其教学特点,如教学内容注重应用、使用有利于培养应用型人才的嵌入式的教学模式、以展开实例的方式教学组织形式等,借鉴美国高校计算机基础教学的经验以促进我国高校计算机基础教学的发展。     

Reportable animal diseases in the United States

Timely reporting of animal diseases is fundamental to the detection of emerging threats, rapid and effective outbreak response, and ultimately the health of both animals and humans. In the United States, each state has the authority to regulate reporting of diseases. While past research has reviewed reportable human diseases, the research on reportable animal diseases has assessed only veterinarian knowledge and understanding of law rather than identifying the actual statutes and regulation that exists. Therefore, this article reviewed the statutes, regulations, and online reportable animal disease lists from the 50 states and District of Columbia to describe the legal landscape of animal disease reporting. The findings suggest wide variation in state animal disease reporting requirements. Three hundred and forty distinct diseases, agents, and categories were identified, with only 15 diseases being listed by 40 or more states. States typically require reporting of animal diseases within 48 h. Substantial consideration needs to be given to the implications of these variations for rapid and effective animal and zoonotic disease detection and reporting in the United States, particularly in light of One Health initiatives and international obligations.